The filter does what he's there: reduce light. However, he is only conditionally usable in daylight in connection with wide-angle. This leads to very strong stray light with reflections of the lens on the filter and thus also in the picture - which makes it unusable in 90% of cases. This can be at normal focal lengths may (not tried) reduce with Geli in wide-angle, it is much more difficult because of the vignetting. I uploaded a sample image for the problem. The problem seems to be in the master filter glass manufacturers. Only Lee has the problem better, according to a report on the internet under control - but with a very different price announcement! Therefore: For Twilight good in daylight / Backlight better not.
